1. Field of the Invention
The invention relates to orthopedic joint replacement and, more particularly, to a prosthetic device for use in orthopedic joint replacement and a system and method for implanting the same.
2. Description of Related Art
As shown in FIG. 1, conventional total knee arthroplasty (TKA) systems typically include a femoral component 500 that is implanted on the distal end of the femur and replaces the bearing surfaces of the femur, a tibial component 502 that is implanted on the proximal end of the tibia and replaces the bearing surfaces of the tibia, and a patellar component (not shown) that replaces the undersurface of the patella. The tibial component 502 typically includes a tibial baseplate (or tray) 502a that is affixed to the bone and a tibial insert 502b that is disposed on the tibial baseplate 502a and forms the bearing surfaces of the tibial component 502. In operation, the bearing surfaces of the femoral component 500 articulate against the bearing surfaces of the tibial component 502 as the knee joint moves through a range of motion.
One disadvantage of conventional TKA systems is that they limit the ability to perform surgery through MIS incisions. For example, the femoral component 500 and the tibial component 502 are too large to fit through minimally invasive surgery (MIS) incisions, which are considerably smaller than incisions used in traditional surgical approaches. Another disadvantage is that the femoral component 500 and the tibial component 502 have fixed geometry and are available in a limited range of sizes. As a result, the surgeon may be unable to achieve an optimal fit for each patient and may be forced to remove healthy as well as diseased bone to accommodate the implant. Thus, conventional TKA systems lack the flexibility to enable the surgeon to select implant components that are customized to accommodate a patient's unique anatomy and/or disease state.
In an effort to overcome these disadvantages, modular knee prostheses comprising multiple components that are inserted separately and assembled within the surgical site have been developed. One example of a modular system is described in U.S. patent application Ser. No. 11/312,741, filed Dec. 30, 2005, which is hereby incorporated by reference herein in its entirety. Computer aided design can be used to create a variety of components, certain of which are intended to provide a more customized fit based on a patient's particular circumstances and characteristics (e.g., anatomy and/or disease state). Such modular systems offer increased flexibility to the surgeon and may result in an improved fit. Such systems present a challenge, however, as they generally require a high degree of insertion accuracy to properly place the components relative to one another. For example, whereas the femoral component 500 of a conventional TKA system comprises a solid part having a fixed geometry (as shown in FIG. 1), a modular system may be constructed of individual modular components that are each separately implanted in the joint. Thus, the geometry of a modular system is variable depending on the surgeon's placement of the separate modular components relative to one another. To ensure that a proper geometric relationship (e.g., distance, orientation, alignment, etc.) is established among all modular components, each modular component must be inserted (or positioned) in the joint with a high degree of accuracy. Achieving the requisite accuracy requires significant surgical skill as well as specialized instruments and technology. Because surgeons have different skill levels and experience, operative results among patients may not be sufficiently predictable and/or repeatable. As a result, modular implant performance and longevity may vary among patients.
Another disadvantage of both conventional and modular knee implants is that monitoring implant wear and relative position over time in a non-invasive manner is difficult. For example, although installed implants may be imaged using X-ray or other imaging technologies, such images do not provide sufficient clarity and/or detail to enable precise tracking of implant wear and relative position. As a result, surgeons are often unable to predict precisely when an implant will need to be replaced or to determine the condition of soft tissue in the joint in a non-invasive manner.
In view of the foregoing, a need exists for techniques and implants that enable improved insertion accuracy and relative placement of implant components and non-invasive monitoring of implant wear and relative position.